Optical component

ABSTRACT

An optical component includes: a first substrate, a second substrate, and a transfer board. A first electrically conductive path is disposed on a top surface of the first substrate. A second electrically conductive path is disposed on a bottom surface of the first substrate. A third electrically conductive path is disposed on a top surface of the second substrate. A microstrip line structure is disposed on the transfer board. The microstrip line structure includes a transfer line disposed on a top surface of the transfer board. The top surface of the second substrate is opposite to the bottom surface of the first substrate, where the second electrically conductive path fits the third electrically conductive path. The transfer board is disposed on the top of the top surface of the second substrate. One end of the transfer line is electrically connected to the first electrically conductive path by a wire bonding.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation under 35 U.S.C. § 120 of U.S. application Ser. No. 14/849,362 filed on Sep. 9, 2015, pending, which claims priority to Chinese Patent Application No. 201510145276.3, filed on Mar. 30, 2015. Each of the aforementioned applications is hereby incorporated by reference in their entireties.

TECHNICAL FIELD

The present disclosure relates to the optical communications field, and in particular, to an optical component.

BACKGROUND

Optical modules and optical components of the optical communications field develop very quickly. With a large number of fiber to the home (FTTH) and 3G/4G network construction in China, the demands on optical modules and optical components are increasing. Therefore, optical modules and optical components characterized by high development speed, long transmission distance, miniaturization, and low power consumption become the focus of device suppliers and component suppliers.

In order to adapt to miniaturization tendency of optical components, encapsulated laser and other electronic components are usually used as an optical component, and a printed circuit board (PCB) outside is connected to the laser and the other electronic components encapsulated inside, so as to supply electric energy to the laser and the other electronic components. Because the PCB supplies electric energy to the laser and the other components through an electrically conductive path between the PCB and the laser and other components, an impedance matching design of each electrically conductive path has a great influence on a high-frequency signal input to the laser.

SUMMARY

An embodiment of the present disclosure provides an optical component, which may meet an impedance matching requirement of high-frequency signal transmission.

An optical component is provided, which comprises a first substrate, a second substrate, and a transfer board; a first electrically conductive path is disposed on a top surface of the first substrate, and a second electrically conductive path is disposed on a bottom surface of the first substrate; a third electrically conductive path is disposed on a top surface of the second substrate; a microstrip line structure is disposed on the transfer board, wherein the microstrip line structure comprises a transfer line disposed on a top surface of the transfer board; the top surface of the second substrate is opposite to the bottom surface of the first substrate, wherein the second electrically conductive path fits the third electrically conductive path, and the transfer board is disposed on the top of the top surface of the second substrate; and one end of the transfer line is electrically connected to the first electrically conductive path by a wire bonding.

An optical device is also provided, which comprises a fiber adapter connected to an optical component comprising: a first substrate comprising a first top surface and a first bottom surface; a second substrate comprising a second top surface and a second bottom surface, and a transfer board comprising a top transfer surface and a bottom transfer surface; wherein a first electrically conductive path is disposed on the first top surface, and a second electrically conductive path is disposed on the first bottom surface wherein a third electrically conductive path is disposed on the second top surface; wherein a microstrip line structure is disposed on the transfer board; the microstrip line structure comprises a transfer line disposed on the top transfer surface; wherein the second top surface is opposite to the first bottom surface; wherein the second electrically conductive path fits the third electrically conductive path; and wherein the transfer board is disposed on the top of the second top surface and located in the third electrically conductive path.

BRIEF DESCRIPTION OF THE DRAWINGS

To illustrate the technical solutions in the embodiments of the present disclosure more clearly, the following briefly introduces the accompanying drawings required for describing the embodiments or the prior art. Apparently, the accompanying drawings in the following description show merely some embodiments of the present disclosure, and a person of ordinary skill in the art may still derive other drawings from these accompanying drawings without creative efforts.

FIG. 1 is an external structural diagram of an optical component according to the prior art;

FIG. 2 is an internal structural diagram of an optical component according to an embodiment of the present disclosure;

FIG. 3 is local structural diagram 1 of the optical component shown in FIG. 2 according to an embodiment of the present disclosure;

FIG. 4 is local structural diagram 2 of the optical component shown in FIG. 2 according to an embodiment of the present disclosure;

FIG. 5 is local structural diagram 3 of the optical component shown in FIG. 2 according to an embodiment of the present disclosure;

FIG. 6 is a structural diagram of a transfer board of the optical component shown in FIG. 2 according to an embodiment of the present disclosure;

FIG. 7 is a cross-section structural diagram of a first substrate and a second substrate of the optical component shown in FIG. 2 according to an embodiment of the present disclosure;

FIG. 8 is a local structural diagram of the optical component shown in FIG. 2 according to another embodiment of the present disclosure;

FIG. 9 is a structural diagram of a first microstrip line structure on a first substrate according to an embodiment of the present disclosure;

FIG. 10 is an A-A′ cross-section structural diagram of the first microstrip line structure shown in FIG. 9 according to an embodiment of the present disclosure;

FIG. 11 is a structural diagram of a microstrip line structure on a transfer board according to an embodiment of the present disclosure;

FIG. 12 is a B-B′ cross-section structural diagram of the microstrip line structure on the transfer board shown in FIG. 11 according to an embodiment of the present disclosure;

FIG. 13 is a structural diagram of a second microstrip line structure on a first substrate according to an embodiment of the present disclosure;

FIG. 14 is a C-C′ cross-section structural diagram of the second microstrip line structure shown in FIG. 13 according to an embodiment of the present disclosure;

FIG. 15 is a structural diagram of a microstrip line structure on a transfer board according to another embodiment of the present disclosure; and

FIG. 16 is a D-D′ cross-section structural diagram of the microstrip line structure on the transfer board shown in FIG. 15 according to an embodiment of the present disclosure.

REFERENCE NUMERAL

fiber adapter—101;

cavity—102;

pin—103 and 104;

laser—105;

anode of the laser—105 a;

heat sink—106;

first microstrip line structure—200;

first substrate—201;

second substrate—202;

transfer board—203;

first electrically conductive path—204 (204 a, 204 b, 204 c, 204 d, 204 e, 204 f, and 204 g)

second electrically conductive path—205;

third electrically conductive path—206;

transfer line—207 (207 a, 207 b, 207 c, 207 d, 207 e, 207 f, and 207 g);

microstrip line structure on the transfer board—300;

first electrically conductive layer—301;

via hole—302 and 303;

second electrically conductive layer—304; and

second microstrip line structure—400.

DETAILED DESCRIPTION

Throughout the specification and claims, terms may have nuanced meanings suggested or implied in context beyond an explicitly stated meaning. Likewise, the phrase “in one embodiment” as used herein does not necessarily refer to the same embodiment and the phrase “in another embodiment” as used herein does not necessarily refer to a different embodiment. It is intended, for example, that claimed subject matter include combinations of example embodiments in whole or in part.

In general, terminology may be understood at least in part from usage in context. For example, terms, such as “and”, “or”, or “and/or,” as used herein may include a variety of meanings that may depend at least in part upon the context in which such terms are used. Typically, “or” if used to associate a list, such as A, B or C, is intended to mean A, B, and C, here used in the inclusive sense, as well as A, B or C, here used in the exclusive sense. In addition, the term “one or more” as used herein, depending at least in part upon context, may be used to describe any feature, structure, or characteristic in a singular sense or may be used to describe combinations of features, structures or characteristics in a plural sense. Similarly, terms, such as “a,” “an,” or “the,” again, may be understood to convey a singular usage or to convey a plural usage, depending at least in part upon context. In addition, the term “based on” may be understood as not necessarily intended to convey an exclusive set of factors and may, instead, allow for existence of additional factors not necessarily expressly described, again, depending at least in part on context.

Various units, circuits, or other components may be described or claimed as “configured to” perform a task or tasks. In such contexts, “configured to” is used to connote structure by indicating that the units/circuits/components include structure (e.g., circuitry) that performs those task or tasks during operation. As such, the unit/circuit/component can be said to be configured to perform the task even when the specified unit/circuit/component is not currently operational (e.g., is not on). The units/circuits/components used with the “configured to” language include hardware—for example, circuits, memory storing program instructions executable to implement the operation, etc. Reciting that a unit/circuit/component is “configured to” perform one or more tasks is expressly intended not to invoke 35 U.S.C. section 112, sixth paragraph, for that unit/circuit/component. Additionally, “configured to” can include generic structure (e.g., generic circuitry) that is manipulated by software and/or firmware (e.g., an FPGA or a general-purpose processor executing software) to operate in manner that is capable of performing the task(s) at issue.

The following clearly and completely describes the technical solutions in the embodiments of the present disclosure with reference to the accompanying drawings in the embodiments of the present disclosure. Apparently, the described embodiments are some of the embodiments of the present disclosure rather than all of the embodiments. All other embodiments obtained by a person of ordinary skill in the art based on the embodiments of the present disclosure without creative efforts shall fall within the protection scope of the present disclosure.

In the description of the present disclosure, it should be understand that positions and positional relationships indicated by the terms such as “center”, “above”, “below”, “in front of”, “behind”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inside”, “outside” are based on the position or positional relationship shown in the accompany drawings, which are used only for convenient and brief description, and do not indicate or imply that the indicated apparatus or element must be in a specific position, and must be constructed and operated in a specific position. In addition, in embodiments of the present disclosure, an inner end and an outer end are both defined according to directions of signals in a transmission path, that is, according to directions of signals in a transmission path, one end for inputting signals is defined as the outer end or a signal input end of the transmission path, and another end for outputting signals is defined as the inner end or a signal output end. Of course, other names may be defined according to principles, and thus the foregoing cannot be understood as a limitation on the present disclosure.

With quick development of optical modules and optical components in the optical communications field, system carries are increasingly demanding on optical modules and optical components. Specific manifestations are as follows: transmission speed is increased from 1.25 G, 2.5 G, 10 G, 40 G to 100 G or higher; a transmission distance is increased from 2 km, 10 km, 40 km to 80 km or farther; for miniaturization, an optical module is evolved from a gigabit interface converter (GBIC), a 10 Gigabit EtherNet Transceiver PAcKage (XENPAK), an X2 (a 10 G optical module evolved from the XENPAK), a 10 Gigabit Small Form Factor Pluggable (XFP) to a small form-factor pluggable (SFP+); and correspondingly, an optical component is evolved from butterfly to a 10 Gbit/s Miniature Device (XMD). An optical component according to the embodiments of the present disclosure is an optical component using an XMD encapsulation manner. Of course, the optical component according to the embodiments of the present disclosure is not limited to the optical component using the XMD encapsulation manner.

As shown in FIG. 1, an encapsulation structure of an optical component according to an embodiment of the present disclosure usually includes a fiber adapter 101, a cavity 102, a laser and other elements encapsulated in the cavity (not shown in FIG. 1). Light from the laser enters a fiber through the fiber adapter 101, and a printed circuit board (PCB) used to supply electric energy is connected to the optical component using pins (103 and 104), so that the optical component is fasten and electric energy is supplied to the laser and other elements.

The laser and other elements inside the optical component are electrically connected to the pins (103 and 104) by using a transfer component in the cavity 102. For details, see FIG. 2, FIG. 3, FIG. 4, FIG. 5, FIG. 6, and FIG. 7. A first substrate 201 is disposed in the cavity 102. As shown in FIG. 3 and FIG. 4, a first electrically conductive path 204 is disposed on a top surface of the first substrate 201, a pin 103 is disposed at an outer end of the first electrically conductive path 204, and an inner end of the first electrically conductive path 204 is connected to an element inside the cavity 102 by using wire bonding.

Because many elements inside the optical component require electric energy supply, multiple first electrically conductive path 204 need to be disposed on the top surface of the first substrate 201. To ensure enough separation distance between each electrically conductive path, multiple electrically conductive paths disposed on the same surface of the same substrate occupy a large width, which affects overall width of the optical component and does not benefit miniaturization of the optical component. Therefore, a second electrically conductive path 205 is disposed on a bottom surface of the first substrate 201, and a pin 104 is disposed at an outer end of the second electrically conductive path 205. However, because wire bonding can be implemented on only one side of the substrate, a second substrate 202 is disposed in the cavity 102, and a third electrically conductive path 206 is disposed on a top surface of the second substrate 202. As shown in FIG. 3, FIG. 4, and FIG. 7, the top surface of the second substrate 202 is opposite to the bottom surface of the first substrate 201, where the second electrically conductive path 205 fits the third electrically conductive path 206, and an inner end of the third electrically conductive path 206 may be connected to the element of the cavity 102 by using the wire bonding. Specifically, an inner end of each second electrically conductive path 205 fits an outer end of a third electrically conductive path 206., and because a signal outputting end of each third electrically conductive path is electrically connected to the elements encapsulated in the optical component, the inner end of the third electrically conductive path needs to be exposed to one side of the first substrate; however, the pin 104 needs to be disposed at the outer end of the second electrically conductive path 205, and thus an outer end of each second electrically conductive path 205 is exposed to one side of the second substrate 202.

Because the second electrically conductive path 205 is fitly electrically connected to the third electrically conductive path 206, which results in low alignment accuracy and cannot ensure impedance matching of the electrically conductive path, they are usually used for transmitting direct current signals. The first electrically conductive path 204 is used for transmitting high frequency signals of the laser. However, the inner end of the third electrically conductive path 206 needs to be exposed to one side of the first substrate, so a wire bonding distance between the first electrically conductive path 204 and a connected element is increased; in addition, shapes and status of wire bonding makes it render an inductance characteristic, which results in impedance mismatching of a signal transmitting channel. To solve the problem of impedance mismatching between a transmission path and a high frequency signal due to too long wire bonding length, a transfer board 203 is disposed in the cavity 102. As shown in FIG. 6, a microstrip line structure is disposed on the transfer board 203, and the microstrip line structure on the transfer board 203 includes a transfer line 207 on a top surface of the transfer board 203. Here, the microstrip may include an electrical transmission line which is fabricated using printed circuit board technology. The microstrip may be used to convey microwave-frequency signals. As shown in FIG. 2, FIG. 3, and FIG. 4, one end of the transfer line 207 is electrically connected to the first electrically conductive path 204 by using the wire bonding, another end of the transfer line 207 is connected to an internal element of the optical component by using the wire bonding, and a pin 204 inputs a high frequency signal to the laser of the optical component through the first electrically conductive path 204 and the transfer line 207. The transfer line included in the microstrip line structure on the transfer board 203 makes a characteristic impedance of the transmitted frequency signal controllable, which solves the problem of impedance mismatching between the transmission path and the high frequency signal due to too long wire bonding length.

The forgoing provided optical component includes the first substrate, the second substrate, and the transfer board. To meet a requirement that the wire bonding can be implemented only on one side of the substrate, all electrically conductive paths requiring the wire bonding: the first electrically conductive path, the third electrically conductive path, and the transfer line are all disposed on one side of a carrier substrate. The third electrically conductive path fits the second electrically conductive path to implement transfer connection. An signal outputting end of each third electrically conductive path is electrically connected to an element encapsulated in the optical component by using the wire bonding; therefore, the signal outputting end of the third electrically conductive path is exposed to one side of the first substrate, so the wire bonding distance between the first electrically conductive path and the connected element is increased, and thus the transfer board is disposed on the top of the top surface of the second substrate and located in the third electrically conductive path, so that the connection between the first electrically conductive path and the element is transferred by using the transfer line on the transfer board. Because the microstrip line structure is disposed on the transfer board, and the microstrip line structure on the transfer board includes the transfer line disposed on the top surface of the transfer board, and the microstrip line structure makes a characteristic impedance of the high frequency signal transmitted in the transfer line controllable. Therefore, in embodiments of the present disclosure, the transfer line and the first eclectically conductive path are set to meet a preset impedance matching requirement, which means that wire bonding length between the first electrically conductive path and the connected element is shorted, so that impedance mismatching between the transmission path and the high frequency signal due to too long wire bonding length is avoided, and thus the impedance matching requirement for high frequency signal transmission is met.

As shown in FIG. 2, the first substrate 201 and the second substrate 202 are installed at one end of the cavity 102 of the optical component, while in FIG. 3, edges of two ends of the electrically conductive path on the first substrate 201 are all flush structures, so a stepped notch 220 is formed at a junction location of the first substrate 201, the second substrate 202, and the cavity 102. The notch 220 may include two side surfaces 220 a and 220 b as shown in FIGS. 3 and 8. As a result, it is difficult to completely seal the cavity 102 during an encapsulation process. In order to completely seal the cavity 102 during the encapsulation process, as shown in FIG. 8, the first substrate 201 includes a notch 220 thereon, and projecting edges of two sides of the notch 220 are aligned with the second substrate 202. The transfer board 203 is at least partially disposed in the notch 220. Referring to the foregoing structure, the inner end of each third electrically conductive path 206 is exposed to the notch 220, and the projecting edges of the two sides of the notch 220 on the first substrate are aligned with the second substrate 202, so that the cavity 102 is completely sealed by utilizing the projecting edges of the two sides of the notch 220.

In addition, FIG. 2 uses laser encapsulation as an example. FIG. 3 further shows a laser 105 and a heat sink 106. A cathode of the laser 105 fits an electrically conductive layer of a surface of the heat sink. An anode 105 a of the laser is disposed on a top surface of the laser 105. Other electrical components are attached on a top surface of the heat sink, for example, a thermistor, a monitor photodiode (MPD), a TEC, and the like. For ease of gold wire bonding, wire bonding height is minimized, and the top surface of the heat sink 106 and the top surface of the second substrate 202 are in the same plane or near the same plane.

In addition, an element similar to the laser needs to be driven by a high frequency signal; however, a path for transmitting the high frequency signal needs to meet the required impedance matching requirement, so as to ensure that the high frequency signal can transmit a point of load completely (such as an anode 105 a of the laser shown in FIG. 3), and would not be reflected in the transmission path. Therefore, quality of the high frequency signal is improved. As shown in FIG. 7, one end of each second electrically conductive path 205 fits one end of the third electrically conductive path 206; however, with a limitation of craft precision, there is no guarantee that the second electrically conductive path 205 and the third electrically conductive path 206 are completely right fit, and when the second electrically conductive path 205 and the third electrically conductive path 206 are not completely right fit, the impedance of the transmission line cannot be guaranteed. Therefore, providing a high frequency signal to the anode 105 a of the laser through the first electrically conductive path 204 on the top surface of the first substrate 201 is prioritized. However, if the electrically conductive path 204 is electrically connected to the anode 105 a of the laser by using a gold wire, the high frequency signal needs to be transmitted to the anode 105 a of the laser through the gold wire of a considerable length. In addition, shapes and status of the gold wire makes it render an inductance characteristic, which results in discontinuous impedance of the signal transmitting path, and transmission bandwidth is seriously limited. Therefore, in embodiments of the present disclosure, the first electrically conductive path 204 is connected to the anode 105 a of the laser by using the transfer line 207 on the transfer board 203. In addition, in order to minimize the diameter of the transmission path between the first electrically conductive path 204 and the laser 105, the transfer board 203 is at least partially disposed in the notch of the first substrate 201, so that the first electrically conductive path 204 is approximately linear connected to the anode 105 a of the laser. In addition, wire bonding using gold wires is used only at a transfer connection position between the transfer line 207 and the anode 105 a of the laser, and at a transfer connection between the transfer line 207 and the first electrically conductive path 204. Therefore, the wire bonding length is minimized. Because the gold wire affects only the transmission of the high frequency signal, on the transfer board 203, only a transfer line used for transmitting the high frequency signal is disposed. In addition, as shown in FIG. 2, thickness of the transfer board may be the same as that of the first substrate. When the thickness of the transfer board is less than that of the substrate, in order to make the inner end of the transfer line on the transfer board as close as possible to the connected element, the outer end of the transfer line is closed to the connected inner end of the first electrically conductive path, and thus the wire bonding length is minimized. As shown in FIG. 2, the inner end of the transfer board may be downward sloping.

The laser includes two types: direct modulation laser and external modulation laser. For a common direct modulation laser, for example, distributed feedback laser (DFB), only a high frequency signal needs to be provided for driving the DFB; and for a common external modulation laser, for example, electro-absorption modulated laser (EML), a high frequency signal and a direct current signal need to be provided for driving the EML. A direct current signal is mainly used to supply power energy to a thermoelectric cooler, send back a thermo-sensitive resistance signal, and send back detection current of a backlight detection unit. When a normal manner is used to input a modulation signal of the laser, a signal may be used to provide a high frequency signal to the anode of the laser, and the cathode of the laser is connected to a ground cable in a common ground manner; or when a differential signal manner is used to input the modulation signal of the laser, a differential signal line of a pair of differential signal lines is used to provide a first high frequency signal to the anode of the laser, and another differential signal line of the pair of differential signal line is used to provide a second high frequency signal to the cathode of the laser. However, a high frequency signal connection needs to comply with a principle that two ground cables (G) encase one or a group of high frequency signal lines (S) to ensure impedance matching between the high frequency signal line (S) and the ground cable (G). Therefore, when a normal manner is used, common connection manners are GSG and GSGSG, and when a differential signal manner is used, the common manner is, for example, GSSG. As shown in FIG. 3 or FIG. 5, the top surface of the first substrate 201 has five first electrically conductive paths 204. When a normal manner is used, any three adjacent first electrically conductive paths 201 may be selected, wherein a middle first electrically conductive path 204 is used to connect to the high frequency signal line (S), and other two first electrically conductive paths 204 adjacent to the high frequency signal line (S) are used to connect to the ground cable (G); in addition, on the top surface of the transfer board, any three transfer lines are selected to connect to the three selected first electrically conductive paths 204 on the top surface of the first substrate 201 respectively, and of course, for the three transfer lines 207 on the top surface of the transfer board 203, a middle transfer line 207 is used to connect to the high frequency signal line (S), and other two transfer lines 207 adjacent to the high frequency signal line (S) are used to connect to the ground cable (G), and thus a GSG form is formed; or when the top surface of the first substrate 201 has five first electrically conductive paths 204 and the top surface of the transfer board 203 has five transfer lines 207, a middle electrically conductive path is used to connect to the ground cable (G), two electrically conductive paths adjacent to the ground cable (G) are used to connect to the high frequency signal line (S), and outermost two electrically conductive paths are used to connect to the ground cable (G), and thus a GSGSG-form high frequency signal connection manner is formed. When a differential signal manner is used, any four adjacent first electrically conductive paths 204 are selected, wherein a middle first electrically conductive path 204 is used to connect to a first high frequency signal line (S), another middle first electrically conductive path 204 is used to connected to a second high frequency signal line (S), and outermost two first electrically conductive paths 204 of the four adjacent first electrically conductive paths 204 are used to connect to the ground cable (G); in addition, on the top surface of the transfer board 203, any four transfer lines 207 are selected to connect to the four selected first electrically conductive paths 204 on the top surface of the first substrate 201 respectively, and of course, for the four transfer lines 207 on the top surface of the transfer board 203, two middle transfer lines 207 are used to connect to the first high frequency signal line (S) and the second high frequency signal line (S) respectively, and outermost two transfer lines 207 of the four transfer lines 207 are used to connect to the ground cable (G), and thus a GSSG-form high frequency connection manner is formed.

Further, when a normal manner is used to input a modulation signal, to prevent deterioration of a high frequency characteristic of a high frequency signal transmitted in a high frequency transmission path on the first substrate 201, the optical component according to the embodiments of the present disclosure further comprises: a first microstrip line structure 200 disposed on the first substrate. As shown in FIG. 9 and FIG. 10, the first substrate 201 is of a multiple layer structure, and the first microstrip line structure 200 includes: three adjacent first electrically conductive paths 204 (204 a, 204 b, and 204 c) on the top surface of the first substrate 201, and a first electrically conductive layer 301 disposed inside the first substrate 201. The first electrically conductive layer 301 is electrically connected to outermost two first electrically conductive paths 204 (204 a and 204 c) of the three adjacent first electrically conductive paths 204 (204 a, 204 b, and 204 c) in the first microstrip line structure 200 through a via hole 302. Optionally, a middle first electrically conductive path 204 b of the three adjacent first electrically conductive paths 204 (204 a, 204 b, and 204 c) in the first microstrip line structure 200 is connected to the anode of the laser by using a transfer line, which is used to transmit a high frequency signal of the anode of the laser; and outermost two first electrically conductive paths (204 a and 204 c) of the three adjacent first electrically conductive paths in the first microstrip line structure 200 are connected to the cathode of the laser by using a transfer line respectively, which is used to connect the cathode of the laser to the ground. As described above, when a high frequency signal is provided in a GSG form, the first electrically conductive path 204 a, the first electrically conductive path 204 c, and the first electrically conductive layer 301 are connected to the ground cable (G), and the first electrically conductive path 204 b is used for the high frequency signal line (S). One side of two sides of the first electrically conductive path 204 b in the first microstrip line structure is an air medium of a low dielectric constant, and another side is the first electrically conductive layer 301 of a high dielectric constant, which is more benefit to the transmission of the high frequency signal. To ensure that electric field lines of the first electrically conductive path 204 b toward the first electrically conductive layer 301 are distributed densely and uniformly, multiple via holes 302 may be set uniformly to electrically connect the first electrically conductive layer 301 to the first electrically conductive paths 204 a and 204 c respectively.

Optionally, as shown in FIG. 11 and FIG. 12, based on an objective similar to the objective described above, to prevent deterioration of a high frequency characteristic of a high frequency signal transmitted in a high frequency transmission path on the transfer board 203, a microstrip line structure 300 on the transfer board 203 according to an embodiment of the present disclosure includes: three adjacent transfer lines 207 on the top surface of the transfer board 203, and a second electrically conductive layer 304 disposed inside the transfer board 203. The second electrically conductive layer 304 is electrically connected to outermost two transfer lines 207 (207 a and 207 c) of the three adjacent transfer lines 207 (207 a, 207 b, and 207 c) in the microstrip line structure 300 on the transfer board 203 through a via hole 303. Optionally, a middle transfer line 207 b of the three adjacent transfer lines 207 (207 a, 207 b, and 207 c) in the first microstrip line structure 300 on the transfer board 203 is connected to an anode of a laser, which is used to transmit a high frequency signal of the anode of the laser; and outermost two transfer lines (207 a and 207 c) of the three adjacent transfer lines 207 (207 a, 207 b, and 207 c) in the microstrip line structure 300 on the transfer board 203 are connected to a cathode of the laser, which is used to connect the cathode of the laser to the ground. As described above, when a high frequency signal is provided in a GSG form, the transfer line 207 a, the transfer line 207 c, and the second electrically conductive layer 304 are connected to the ground cable (G), and the transfer line 207 b is used for the high frequency signal line (S). One side of two sides of the transfer line 207 b in the second microstrip line structure is an air medium of a low dielectric constant, and another side is the third electrically conductive layer 304 of a high dielectric constant, which is more benefit to the transmission of the high frequency signal. To ensure that electric field lines of the transfer line 207 b toward the second electrically conductive layer 304 are distributed densely and uniformly, multiple via holes 303 may be set uniformly to electrically connect the second electrically conductive layer 302 to the transfer lines 207 b and 207 c respectively.

Further, when a differential signal manner is used to input a modulation signal, to prevent deterioration of a high frequency characteristic of a high frequency signal transmitted in a high frequency transmission path on the first substrate 201, as shown in FIG. 13 and FIG. 14, the first substrate 201 according to the embodiments of the present disclosure is of a multiple layer structure, and the substrate 201 includes a second microstrip line structure 400 thereon. The second microstrip line structure 400 includes: four adjacent first electrically conductive paths 204 (204 d, 204 e, 204 f, and 204 g) on the top surface of the first substrate 201, and a first electrically conductive layer 301 disposed inside the first substrate 201. The first electrically conductive layer 301 is electrically connected to outermost two first electrically conductive paths 204 (204 d and 204 g) of the four adjacent first electrically conductive paths 204 (204 d, 204 e, 204 f, and 204 g) in the second microstrip line structure 400 through a via hole 302. Optionally, a middle first electrically conductive path 204 e of the four adjacent first electrically conductive path 204 (204 d, 204 e, 204 f, and 204 g) in the second microstrip line structure 400 is connected to an anode of a laser by using a transfer line, which is used to transmit a first high frequency signal of the anode of the laser; another middle first electrically conductive path 204 f of the four adjacent first electrically conductive paths 204 (204 d, 204 e, 204 f, and 204 g) in the second microstrip line structure 400 is connected to a cathode of the laser by using a transfer line, which is used to transmit a second high frequency signal of the cathode of the laser; and outermost two first electrically conductive paths 204 d and 204 g of the four adjacent first electrically conductive paths 204 (204 d, 204 e, 204 f, and 204 g) are connected to the ground. As described above, when a high frequency signal is provided in a GSSG form, the first electrically conductive path 204 d, the first electrically conductive path 204 g, and the first electrically conductive layer 301 are connected to the ground cable (G). The first electrically conductive path 204 e and the first electrically conductive path 204 f construct a differential signal transmission path. One side of two sides of the first electrically conductive path 204 e and the first electrically conductive path 204 f in the second microstrip line structure is an air medium of a low dielectric constant, and another side is the first electrically conductive layer 301 of a high dielectric constant, which is more benefit to the transmission of the high frequency signal. To ensure that electric field lines of the first electrically conductive path 204 e and 204 f toward the first electrically conductive layer 301 are distributed densely and uniformly, multiple via holes 302 may be set uniformly to electrically connect the first electrically conductive layer 301 to the first electrically conductive paths 204 d and 204 g respectively.

Optionally, as shown in FIG. 15 and FIG. 16, based on an objective similar to the objective described above, to prevent deterioration of a high frequency characteristic of a high frequency signal transmitted in a high frequency transmission path on the transfer board 203, a microstrip line structure 300 on the transfer board 203 according to an embodiment of the present disclosure includes: four adjacent transfer lines 207 on the top surface of the transfer board 203, and a second electrically conductive layer 304 inside the transfer board 203. The second electrically conductive layer 304 is electrically connected to outermost two transfer lines 207 (207 d and 207 g) of the four adjacent transfer lines 207 (207 d, 207 e, 207 f, and 207 g) in the microstrip line structure 300 on the transfer board 203 through a via hole 303. Optionally, a middle transfer line 207 e of the four adjacent transfer lines 207 (207 d, 207 e, 207 f, and 207 g) in the microstrip line structure 300 on the transfer board 203 is connected to an anode of a laser, which is used to transmit a first high frequency signal of the anode of the laser; and another middle transfer line 207 f of the four adjacent transfer lines 207 (207 d, 207 e, 207 f, and 207 g) in the microstrip line structure 300 on the transfer board 203 is connected to a cathode of the laser, which is used to transmit a second high frequency signal of the cathode of the laser; outermost two transfer lines 207 e and 207 f of the four adjacent transfer lines 207 (207 d, 207 e, 207 f, and 207 g) are connected to a first electrically conductive path connected to the ground respectively. As described above, when a high frequency signal is provided in a GSSG form, the transfer line 207 d, the transfer line 207 g, and the second electrically conductive layer 304 are connected to the ground cable (G). The transfer line 207 e and the transfer line 207 f construct a differential signal transmission path. One side of two sides of the transfer line 207 e and the transfer line 207 f in the microstrip line structure 300 on the transfer board 203 is an air medium of a low dielectric constant, and another side is the third electrically conductive layer 304 of a high dielectric constant, which is more benefit to the transmission of the high frequency signal. To ensure that electric field lines of the transfer lines 207 e and 207 f toward the second electrically conductive layer 304 are distributed densely and uniformly, multiple via holes 303 may be set uniformly to electrically connect the second electrically conductive layer 302 to the transfer lines 207 d and 207 g respectively.

The foregoing descriptions are merely specific embodiments of the present disclosure, but are not intended to limit the protection scope of the present disclosure. Any variation or replacement readily figured out by a person skilled in the art within the technical scope disclosed in the present disclosure shall fall within the protection scope of the present disclosure. Therefore, the protection scope of the present disclosure shall be subject to the appended claims.

It is therefore intended that the foregoing description be regarded as illustrative rather than limiting, and that it be understood that it is the following claims, including all equivalents, that are intended to define the spirit and scope of this invention. 

What is claimed is:
 1. An optical module, comprising: a first substrate comprising a first microstrip line comprising a first electrically conductive layer disposed inside the first substrate, a first electrically conductive path disposed on a top surface of the first substrate; a second substrate, wherein a top surface of the second substrate is opposite to a bottom surface of the first substrate; and a transfer board comprising a first end and a second end, the transfer board obliquely disposed relative to the first substrate, the first end of the transfer board disposed adjacent to the top surface of the first substrate, a second microstrip line comprising a transfer line disposed on a top surface of the transfer board, wherein a first end of the transfer line at the first end of the transfer board is electrically connected to the first electrically conductive path by a wire bonding.
 2. The optical module according to claim 1, further comprising: a second electrically conductive path disposed on the bottom surface of the first substrate; and a third electrically conductive path disposed on the top surface of the second substrate, wherein the third electrically conductive path fits the second electrically conductive path.
 3. The optical module according to claim 2, wherein: the first microstrip line comprises three adjacent first electrically conductive paths on the top surface of the first substrate; the first electrically conductive layer is electrically connected to a first electrically conductive path of the adjacent first electrically conductive paths through a first via hole; and the first electrically conductive layer is electrically connected to a second electrically conductive path of the adjacent first electrically conductive paths through a second via hole.
 4. The optical module according to claim 3, wherein: a third electrically conductive path of the three adjacent first electrically conductive paths is disposed between the first and the second electrically conductive paths of the adjacent first electrically conductive paths.
 5. The optical module according to claim 3, wherein: a third electrically conductive path of the adjacent first electrically conductive paths is connected to an anode of a laser by using the transfer line; and the first and the second electrically conductive paths of the adjacent first electrically conductive paths are connected to a cathode of the laser by using the transfer line.
 6. The optical module according to claim 1, wherein: the first microstrip line comprises four adjacent first electrically conductive paths on the top surface of the first substrate; and the first electrically conductive layer is electrically connected to a first electrically conductive path of the adjacent first electrically conductive paths through a first via hole; and the first electrically conductive layer is electrically connected to a second electrically conductive path of the adjacent first electrically conductive paths through a second via hole.
 7. The optical module according to claim 6, wherein: a third electrically conductive path of the adjacent first electrically conductive paths is disposed adjacent to a fourth electrically conductive path of the adjacent first electrically conductive paths; and the third and fourth electrically conductive paths of the adjacent first electrically conductive paths are disposed between the first and the second electrically conductive paths of the adjacent first electrically conductive paths.
 8. The optical module according to claim 6, wherein a third and a fourth electrically conductive paths of the adjacent first electrically conductive paths are connected to an anode of a laser by using the transfer line; and the first and the second electrically conductive paths of the adjacent first electrically conductive paths are connected to a cathode of the laser by using the transfer line.
 9. The optical module according to claim 1, wherein the second microstrip line on the transfer board comprises: three adjacent transfer lines on the top surface of the transfer board, and a second electrically conductive layer disposed inside the transfer board, wherein: the second electrically conductive layer is electrically connected to a first transfer line of the adjacent transfer lines in the second microstrip line through a first via hole, and the second electrically conductive layer is electrically connected to a second transfer line of the adjacent transfer lines in the second microstrip line through a second via hole.
 10. The optical module according to claim 9, wherein: a third transfer line of the adjacent transfer lines in the second microstrip line is disposed between the first and the second transfer line of the adjacent transfer lines.
 11. The optical module according to claim 9, wherein: a third transfer line of the adjacent transfer lines in the second microstrip line on the transfer board is connected to an anode of an laser; and the first and the second transfer lines of the adjacent transfer lines in the second microstrip line on the transfer board are connected to a cathode of the laser.
 12. The optical module according to claim 1, wherein the second microstrip line on the transfer board comprises: four adjacent transfer lines on the top surface of the transfer board, and a second electrically conductive layer disposed inside the transfer board, wherein: the second electrically conductive layer is electrically connected to a first transfer line of the adjacent transfer lines in the second microstrip line through a first via hole, and the second electrically conductive layer is electrically connected to a second transfer line of the adjacent transfer lines in the second microstrip line through a second via hole.
 13. The optical module according to claim 12, wherein: a third transfer line of the adjacent transfer lines in the second microstrip line is disposed adjacent to a fourth transfer line of the adjacent transfer lines; and the third and the fourth transfer lines of the adjacent transfer lines in the second microstrip line are disposed between the first and the second transfer lines of the adjacent transfer lines.
 14. The optical module according to claim 12, wherein: a third and a fourth transfer lines of the adjacent transfer lines in the second microstrip line on the transfer board are connected to an anode of an laser; and the first and the second transfer lines of the adjacent transfer lines in the second microstrip line on the transfer board are connected to a cathode of the laser.
 15. The optical module according to claim 1, wherein: the first substrate comprises a notch, where projecting edges of two sides of the notch are aligned with the second substrate; and the transfer board is at least partially disposed in the notch.
 16. An optical module, comprising: a first substrate comprising a first microstrip line comprising a first electrically conductive layer disposed inside the first substrate; a second substrate, wherein a top surface of the second substrate is opposite to a bottom surface of the first substrate; a transfer board disposed on top of the top surface of the second substrate; a first electrically conductive path disposed on a top surface of the first substrate; a second electrically conductive path disposed on the bottom surface of the first substrate; a third electrically conductive path disposed on the top surface of the second substrate, wherein the third electrically conductive path fits the second electrically conductive path; and a second microstrip line disposed on the transfer board, wherein the second microstrip line comprises a transfer line disposed on a top surface of the transfer board, wherein one end of the transfer line is electrically connected to the first electrically conductive path by a wire bonding, wherein: the first microstrip line comprises five adjacent first electrically conductive paths on the top surface of the first substrate; and the first electrically conductive layer is electrically connected to a first electrically conductive path of the adjacent first electrically conductive paths through a first via hole; the first electrically conductive layer is electrically connected to a second electrically conductive path of the adjacent first electrically conductive paths through a second via hole; and the first electrically conductive layer is electrically connected to a third electrically conductive path of the adjacent first electrically conductive paths through a third via hole.
 17. The optical module according to claim 16, wherein: a fourth electrically conductive path of the adjacent first electrically conductive paths is disposed between the first and the second electrically conductive paths of the adjacent first electrically conductive paths; and a fifth electrically conductive path of the adjacent first electrically conductive paths is disposed between the second and the third electrically conductive paths of the adjacent first electrically conductive paths.
 18. The optical module according to claim 16, wherein a fourth and a fifth electrically conductive paths of the adjacent first electrically conductive paths are connected to an anode of a laser by using the transfer line; and the first, the second, and the third electrically conductive paths of the adjacent first electrically conductive paths are connected to a cathode of the laser by using the transfer line.
 19. An optical device, comprising: a fiber adapter connected to an optical module, the optical module comprising: a first substrate comprising a first microstrip line comprising a first electrically conductive layer disposed inside the first substrate; a second substrate, wherein a top surface of the second substrate is opposite to a bottom surface of the first substrate; a transfer board disposed on top of the top surface of the second substrate; a first electrically conductive path disposed on a top surface of the first substrate; a second electrically conductive path disposed on the bottom surface of the first substrate; a third electrically conductive path disposed on the top surface of the second substrate, wherein the third electrically conductive path fits the second electrically conductive path; and a second microstrip line disposed on the transfer board, wherein the second microstrip line comprises a transfer line disposed on a top surface of the transfer board, wherein one end of the transfer line is electrically connected to the first electrically conductive path by a wire bonding. 